Rotom is a very potent Ghost-type! I recommend using him! You picked a good form too (Not the best, mind you, but Levitate helps it out. It learns some cool Electric-type moves to slow down opponents, and then some tricky Ghost and Dark-type moves to mess them up while they're crippled. I'd use Rotom!
However, if you want some different Electric-types, I'd choose between Magneton, Jolteon, and Manectric.
Magneton may not be fully evolved, but it still has a very respectable Special stat and 10 more Speed points than Magneone, meaning it's a better user for Steel-trapping and using Thunder Wave.
Jolteon is lightning-fast, no question. It can set up Rain Dance itself, then hit with powerful Thunder attacks. Pin Missle can break Substitutes, and Hidden Power (Water) Gets a Rain boost, and OHKO's Ground-types. HP (Grass) is an option for Bulky Waters.
Finally, Manectric is the most balanced of the three, and it's got a pretty cool movepool, as well! I'd recommend a Mental Herb with Thunderbolt, Signal Beam, Magnet Rise, and Overheat.